Star Wars Laser

I have a Star Wars Battle Scene. A moving ship fires a laser beam. OK when the emitter is not moving, but the ship then moves under the beam at its origin and it looks silly. But if I try to move the emitter with the ship the beam turns back into particles (destructive interference??)

OK, to get around this I now offset the layer the beam is on, I track the ship and all looks great!

But as the laser beam hits its target the beam ought to end, OK I use a blocker, great! But the blocker has to be on the moving offset layer and so 'runs away' from the beam.

Question (finally) Is there any simple way to keep the blocker on a moving offset layer stationary? Failing that, what is the technique to 'offset' the offset, if you get my drift?

You could put the Blocker on a second layer, right-click on it, go into its Properties, and choose "Use layers below for bg image". That'll display the background image of your scene if you have one, and still block your particles. And since its not on the layer that is being offset, you don't have to worry about it running away on you.

But from how you described your seen, you could turn on Attached to Emitter on the laser emitter rather than using the Offset. That way you can move the emitter and have the blast follow with it.

And rather than using a Blocker to stop the blast where you want it to end, you should be able to just trim down its Life so that it stops at the right place.

Those tips worked beautifully, thanks a lot. Annoying really as I'd just read about 'attach to emitter' but it hadn't connected...

Not sure that the 'life' idea would work as the emitter is moving and so its end point should move if it has a fixed life. I suppose I could try to match the life to the frame number but I think the blocker may be better especially as the target is actually a slower moving ship.

I'm having loads of fun with this. I'd normally use Cinema 4d to make the explosions but that PI is so much better and so fast!